Many have said the health and social care bill will ruin the NHS. Where do doctors stand? This doctor opposes the bill. It will reduce the health secretary's duty to provide a comprehensive, universal service in England, sell off NHS services to "any willing provider" and replace co-operation with competition (euphemism: "choice"). The £20bn of "efficiencies" demanded over five years will mean the NHS shrinks. The better off will buy "health top-ups", perhaps supported by private insurance schemes to pay for them. The rest will have an NHS safety-net service only.

Polls and conference resolutions demonstrate much disquiet among doctors about the race towards privatisation. Making GPs responsible for the treatments you can or cannot receive will move GPs from impartial, generally trusted patient advocate to guardians of their referral budgets. Some "doctorpreneurs" have stakes in private health providers. GPs' decisions about you will no longer be impartial or trusted. Doctors and the public are increasingly concerned about this; trust is crucial to therapeutic relationships.

Two GP organisations, the National Association of Primary Care (NAPC) with close government links and the NHS Alliance – a naive implementer of governments' policies – are in favour with Andrew Lansley. They contain the GP enthusiasts for getting their hands on the levers of power – allegedly. Allegedly because commissioning groups (CGs) will have little commissioning power after the enormous bureaucracy being created – the NHS commissioning board and regional outposts, remnants of primary care trusts, health and well-being boards and clinical senates – has told them what they can and cannot do.

The BMA is about to launch (a little late perhaps) a public campaign for the bill to be withdrawn. It refuses to oppose the bill so it can stay in negotiation with government rather than leaving the field open to NAPC and the NHS Alliance. The BMA acknowledges it will end in tears and wants to stay "in touch" to help stitch the NHS back together.

Hospital consultants generally dislike the bill. First, it forces their hospitals to become foundation trusts (FTs) – free-standing businesses in full competition with multinational, private providers. Services within FTs will be allowed to fail in a full-blown, winners and losers, NHS market. Second, they fear the alleged power to be handed to GPs and third, because the majority support a publicly funded and provided NHS in common with most doctors.

The BMA GPs' committee (GPC) sees the dangers of the bill but supports its commissioning clauses – the illusion of power still lingers. It sees itself as holding back the tide of privatisation and able to make more humane cuts to services than if the private sector controlled the CGs. In fact, CGs' managerial support is likely to come from the private sector. How long before "GP power" is overwhelmed by private-sector honed, bottom-line focused managers?

Further, the GPC now accepts that CGs will do little actual commissioning. Instead they will have lots of time to ensure that GPs and their practices stick to ever tighter budgets, cram more patients into already congested surgeries and refer fewer patients as draconian "criteria" are forced on them by GP "colleagues" in CGs.

"Ordinary" GPs have reluctantly joined their shadow CGs, allowing Lansley to falsely claim GP popularity for his bill. To show he is wrong I have launched a petition for GPs to state that their involvement in commissioning is to defend their patients and the NHS, not to support the bill that they oppose.

The NHS has served us well. It can improve but we know where privatisation leads, especially when linked to a falling budget and a watered-down government "duty to provide". Doctors get an 88% trust rating; politicians 14%. Doctors say withdraw the bill. We should be saying it loudly and repeatedly.